U.S. Pat. No. 2,982,749 relates to inverse suspension polymerization of water-soluble unsaturated monomers. The U.S. Pat. teaches that an aqueous solution of the unsaturated monomer is suspended in an oil phase and polymerized therein to give polymeric products in bead form. The bead size is controlled by a suspending agent. The suspending agent is a solid or liquid substance having a low hydrophile-lyophile balance. Ethyl cellulose and other organic polymers which have some hydrophilic substituents but predominantly hydrophobic substituents are mentioned as suspending agents. The suspended monomer is heat-polymerized in the presence of a polymerization initiator. Various neutral and anionic monomers are listed; the cationic vinylbenzyl trimethyl ammonium chloride is also mentioned, among others.
German Offenlegungsschrift 2,009,218 also relates to the polymerization of ethylenically unsaturated monomers in a liquid phase which is suspended in a liquid organic medium in the presence of initiators and suspending stabilizers. The liquid monomer phase may consist of an aqueous solution of an ethylenically unsaturated monomer which is not soluble in the organic medium. The suspension stabilizer has a molecule portion which is solvated by the organic medium and another molecule portion which is solvated by the aqueous monomer phase. Examples of neutral, anionic and cationic monomers are listed, such as dialkylaminoalkyl esters or amides of acrylic or methacrylic acid, for example dimethylaminoethyl methacrylate, beta-morpholinoethyl acrylate or diethylaminomethyl methacrylamide. Salts of these monomers containing amino groups with acids, such as hydrochloric acid and the quaternization products which are obtained by reacting the monomers containing amino groups with an alkyl halide are also mentioned.
U.S. Pat. No. 4,151,202 relates to the production of pure diallyl dimethyl ammonium chloride (DADMAC). In the disclosed method DADMAC is produced from allyl chloride of high purity. Pure DADMAC is then polymerized in water according to a solution polymerization process using a free radical catalyst.
U.S. Pat. No. 3,920,599 relates to a water-in-oil emulsion of a DADMAC homopolymer or a copolymer of DADMAC and acrylamide which has been prepared by polymerization in the presence of a low HLB emulsifier, such as sorbitan monooleate, and a free radical initiator.
U.S. Pat. No. 4,439,580 discloses a process for preparing high molecular weight water-in-oil polymer emulsions. Cationic monomers of the type disclosed by formula I are used for the production of the polymers. The U.S. Patent teaches that the polymerization at a pH of 7 to 13 and the addition of a salt is critical. The polymerization is carried out in the presence of a surfactant which is selected from low HLB (hydrophile/lipophile balance) surfactants as summarized in McCutcheon's "Detergents and Emulsifiers", 1978 edition, MC publishing company, pages 17-23.
However, in various trials made by the applicants of polymerizing an aqueous solution of a water-soluble monomer of formula I in a water-immiscible inert organic liquid in the presence of various emulsifiers, unstable emulsions were obtained during polymerization and agglomerations took place at the walls of the reactor.
One object of the present invention is a process for polymerizing monomers of formula I wherein agglomerations of particles are minimized or avoided.